/Engine/Source/Runtime/Core/Public/Math/TransformNonVectorized.h
Transform a rotation. For example if this is a LocalToWorld transform, TransformRotation(Q) would transform Q from local to world space.
[TQuat](API\Runtime\Core\Math\TQuat)< T > TransformRotation ( const [TQuat](API\Runtime\Core\Math\TQuat)< T > & Q ) const